Lasers have become useful in a number of applications. For example, lasers may be used in optical communications to transmit digital data across a fiber-optic network. The laser or laser light emitted therefrom may be modulated by a modulation signal, such as an electronic digital signal, to produce an optical signal transmitted on a fiber-optic cable. An optically sensitive device, such as a photodiode, is used to convert the optical signal to an electronic digital signal transmitted through the fiber-optic network. Such fiber-optic networks enable modern computing devices to communicate at high speeds and over long distances.
Communication modules, such as electronic or optoelectronic transmitters, transceivers, or transponder modules are increasingly used in electronic and optoelectronic communication. Communication modules often communicate with a host computing device via a printed circuit board (PCB) by transmitting and/or receiving electrical data signals to and/or from the host computing device PCB. The electrical data signals can also be transmitted by the communication module outside a host device as optical and/or electrical data signals. Many communication modules include an optical subassembly (OSA) such as a transmitter optical subassembly (TOSA) and/or receiver optical subassembly (ROSA) to convert between the electrical and optical domains.
Generally, TOSA transforms an electrical signal received from the host computing device to an optical signal that is transmitted onto an optical fiber or other transmission medium. A laser diode or similar optical transmitter included in the TOSA is driven to emit the optical signal representing the electrical signal received from the host computing device. A ROSA transforms an optical signal received from an optical fiber or another source to an electrical signal that is provided to the host computing device. A photodiode or similar optical receiver included in the ROSA transforms the optical signal to the electrical signal.
The communication modules having the TOSA and/or ROSA can be implemented, for example, in high power computing applications such as between elements in data centers. In particular, a TOSA can include vertical-cavity surface-emitting lasers (VCSELs) positioned in a first element. A single mode VCSEL can transmit optical signal having a single wavelength along a single mode (SM) fiber. Also, a multimode VCSELs transmit optical signals having multiple wavelengths along a multimode (MM) fiber. The optical fibers can be connected to an ROSA in a second network element. The ROSA can include one or an array of pin photodiodes, for example. The ROSA can receive the optical signals from the TOSA over the optical fibers.
However, the power consumption requirements for the TOSA and/or ROSA optical interconnects are decreasing as the number of such optical interconnects increases. Thus, in data centers and in other high power computing applications, the optical interconnects act as power bottlenecks.
Recently, silicon photonics have been demonstrated as an alternative technology, which can form the basis of some optical interconnects. Generally, silicon photonics enable the communication of optical signals through a photonic circuit built on the silicon substrate. Because silicon substrates are already a medium of an electrical integrated circuit (IC), the incorporation of optical components into a silicon chip with electrical elements can be obtained using silicon photonics to form a photonic integrated circuit (PIC).
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.